IRImplementing rule
21.A.804Identification of parts, appliances, and control and monitoring unit (CMU) components
(a)Each part or appliance which is eligible for installation in a type-certified product, and each CMU component which is eligible for installation in a CMU certified in accordance with this Annex I, shall be permanently and legibly marked with:
1.a name, trademark, or symbol identifying the manufacturer in a manner identified by the applicable design data;
2.the part number, as defined in the applicable design data; and
3.the letters ‘EPA’:
(i)for parts or appliances produced in accordance with approved design data that does not belong to the type-certificate holder of the related product, except for ETSO articles and for parts and appliances covered under point 21.A.307(b);
(ii)for CMU components produced in accordance with approved design data that does not belong to the type-certificate holder of the related CMU, or to the UA type-certificate holder when the CMU is certified as part of the UA, except for ETSO CMU components and CMU components covered under point 21.A.308(b).
(b)By way of derogation from point (a), if the Agency agrees that a part, appliance or a CMU component is too small, or that it is otherwise impractical to mark a part, appliance or a CMU component with any of the information required by point (a), the authorised release document that accompanies the part, appliance or the CMU component or its container shall include the information that could not be marked on the part, appliance or CMU component.
IR · 21.A.804 — Regulation (EU) No 748/2012 · Regulation (EU) 2024/1108 · Initial Airworthiness Easy Access Rules · EAR revision 27 Nov 2025